Low temperature sintering ceramic composition for high frequency, method of fabricating the same and electronic component

ABSTRACT

A low temperature sintering ceramic composition can be sintered at 850 to 1,000° C., and the sintered ceramic has a low dielectric constant (9 or less at 16 Ghz or more) and a high Qf (10,000 or more). The composition can be co-sintered with wiring material containing Ag, Au, or Cu. The ceramic composition includes (by mass) CaO, MgO, and SiO 2  in total: over 60% to 98.6%; Bi 2 O 3 : from 1% to under 35%; and Li 2 O: from 0.4% to under 6%; wherein (CaO+MgO) and SiO 2  are contained in the molar ratio of from 1:1 to under 1:2.5.

This application is a 35 U.S.C. § 371 U.S. National Stage Application ofInternational Application No. PCT/JP2004/005296, filed on Apr. 14, 2004,claiming the priority of Japanese Patent Application No. 2003-110244,filed Apr. 15, 2003, the entire disclosures of which are incorporatedherein by reference in their entireties.

TECHNICAL FIELD

The present invention relates to a low temperature sintering ceramic(porcelain) composition having a low dielectric constant and a lowdielectric loss for high frequency use, an electronic component usingthe same and relates to a fabricating method of the low temperaturesintering ceramic.

BACKGROUND ART

In recent years, the arrival of a new era of information disseminationhas required a high operation speed, high integration, and a highmounting density of a semiconductor device. In order to make asemiconductor device operate at a higher speed, it is indispensable toincrease the signal propagation velocity on the circuit in addition toshortening the length of the wiring in the device. In this connection,the signal propagation velocity is inversely proportional to the squareroot of the relative dielectric constant of substrate material. For thisreason, substrate material having a lower dielectric constant isbecoming necessary. Furthermore, in order to attain the higherintegration and the higher packaging density thereof, wiring materialhaving low resistivity (Ag, Au, Cu, and the like) must be used. However,because these metals have a low melting point, it is necessary to usesubstrate material capable of sintering at a low temperature in thefabrication of a multi-layered printed wiring board that is obtained bysintering the substrate after the wiring pattern was printed thereon.For this reason, an alumina substrate (its dielectric constant: 9 to9.5, and sintering temperature: approximately 1,500° C.) that has beenso far widely used as substrate material for electronic component useare not applicable to high frequency printed circuit boards. Materialthat is other than this material, namely has a lower dielectric constantand can be sintered at a low temperature is required. In addition, thereduction of loss in a microwave zone and a millimeter-wave zone hasbeen also required of the substrate material.

Therefore, recently, glass ceramic material composed of glass andinorganic filler has been studied for substrate material having a lowdielectric constant, which can meet the increase of the operation speed.This type of glass ceramic material is suitable for insulatingsubstrates for high frequency use because of having a low dielectricconstant of 3 to 7, and can be advantageously co-sintered with Ag, Au,Cu, and the like each having a low conductor resistance, because thematerial can be sintered at a temperature of 800 to 1,000° C.

For example, JP-A-2000-188017 (U.S. Pat. No. 6,232,251), discloses aceramic composition for high frequency use that includes a glass phasecapable of precipitating a diopside (CaMgSi₂O₆) type crystal phase andan oxide containing Mg and/or Zn and Ti as the filler, and that can besintered at a temperature of 1,000° C. or less. Furthermore,JP-A-2001-240470 discloses a printed wiring board for high frequency usethat is composed of a crystallized glass component containing SiO₂,Al₂O₃, MO (M denotes an alkaline earth metal element), and Pb, and atleast one type of filler selected from a group of Al₂O₃, SiO₂, MgTiO₃,(Mg, Zn) TiO₃, TiO₂, SrTiO₃, MgAl₂O₄, ZnAl₂O₄, cordierite, mullite,enstatite, willemite, CaAl₂Si₂O₈, SrAl₂Si₂O₈, (Sr, Ca)Al₂Si₂O₈, andforsterite.

In addition, low temperature sintering ceramic compositions in whichboron (B) is used as a sintering aide has been proposed (SeeJP-A-2002-037661, JP-A-2002-173367, etc.).

However, the above-described glass ceramic material, though having a lowdielectric constant, has a high dielectric loss (tanδ) of approximately2×10⁻³ or more in a high frequency zone of a signal frequency of 10 GHzor more, that is, substantially in the range of 5×10³ to 8×10³ in termsof Qf value; accordingly, it does not have the characteristics enough tobe put into practical use as the substrate material for high frequencyuse. For example, the ceramic composition of JP-A-2000-037661 has a Qfvalue of at most 0.5×10³ and the composition of JP-A-2002-173367 has aQf value on the order of 5×10³. Here, the Qf value denotes a product ofa measuring frequency (f/GHz) and Q (≅1/tanδ).

Moreover, JP-A-2001-278657 discloses a low temperature sintering ceramiccomposition that includes a diopside crystal (CaMgSi₂O₆) phase servingas the main crystal phase, characterized in that the dielectric constantε of the composition is 7 or less, and the Qf value thereof is 10,000GHz or more. However, the composition disclosed JP-A-2001-278657essentially requires being subjected to calcining treatment at 1,100° C.or more, which increases the energy cost and the environmental load whenmanufacturing the substrate.

For this reason, an object of the present invention is to provide a lowtemperature sintering ceramic composition that can be co-sintered with alow resistance metal such as Ag, Au, Cu, and the like, reduce the energycost and the environmental load required when manufacturing the ceramictherefrom, and moreover realize the low dielectric constant and the lowdielectric loss in a high frequency region, and to provide a fabricatingmethod of the low temperature sintering ceramic.

DISCLOSURE OF THE INVENTION

The present inventors, after studying hard to overcome the problems,found that a composition in which Bi₂O₃ and Li₂O were added to oxides ofCa, Mg, and Si can be sintered at a temperature in the range of 850 to1,000° C., and a low temperature sintering ceramic obtained by sinteringsuch a composition has a low dielectric constant and a low dielectricloss without being calcined at a high temperature, and therebyaccomplished the present invention.

The present invention provides the following low temperature sinteringceramic composition and fabricating method of a low temperaturesintering ceramic.

(1) A low temperature sintering ceramic composition including thefollowing chemical composition based on percent by mass: CaO, MgO, andSiO₂ in total: over 60% to 98.6%, wherein either of CaO and MgO may notbe contained; Bi₂O₃: from 1% to under 35%; and Li₂O: from 0.4% to under6%; wherein (CaO+MgO) and SiO₂ are contained in the molar ratio of from1:1 to under 1:2.5.(2) A low temperature sintering ceramic composition as described in (1),wherein CaO, MgO, and SiO₂ are contained at least in part as a complexoxide of Ca and/or Mg and Si.(3) A low temperature sintering ceramic composition as described in (2),wherein the complex oxide containing Ca and/or Mg and Si includes adiopside (CaO·MgO·2SiO₂) system crystal phase, an enstatite (MgO·SiO₂)system crystal phase, and/or a wollastonite (CaO·SiO₂) system crystalphase.(4) A low temperature sintering ceramic composition as described in (1),(2), or (3) wherein the low temperature sintering ceramic compositionhas a dielectric constant of 9.0 or less and a Qf value of 10,000 ormore, at 16 GHz or more.(5) An electronic component comprising a wiring pattern on the lowtemperature sintering ceramic composition according to any one of above1 to 4.(6) The electronic component according to above 5, wherein the wiring isformed by sintering a conductive paste containing at lease one metalselected from Ag, Au and Cu.(7) A fabricating method of a low temperature sintering ceramiccomposition including: mixing a raw material powder comprising thefollowing chemical composition based on percent by mass: CaO, MgO, andSiO₂ in total: over 60% to 98.6%, wherein either of CaO and MgO may notbe contained; Bi₂O₃: 1% to under 35%; and Li₂O: from 0.4% to under 6%,such that (CaO+MgO) and SiO₂ are contained in the molar ratio of from1:1 to under 1:2.5; calcining the mixture below 850° C.; molding thematerial powder into a predetermined shape; and sintering the moldedmaterial powder at a temperature of 850° C. to 1,000° C.(8) The method according to above 8, wherein the raw material powdersare fine powders having a particle size of 2.0 μm or less.

DETAILED DESCRIPTION OF THE INVENTION

(A) Ceramic Composition

A low temperature sintering ceramic composition according to theinvention is a low temperature sintering ceramic composition includingthe following chemical composition based on percent by mass: CaO, Mgo,and SiO₂ in total: over 60% to 98.6%, wherein either of CaO and MgO maynot be contained; Bi₂O₃: from 1% to under 35%; and Li₂O: from 0.4% tounder 6%; wherein (CaO+MgO) and SiO₂ are contained in the molar ratio offrom 1:1 to under 1:2.5, and preferably CaO, MgO, and SiO₂ are containedat least in part as a complex oxide of Ca and/or Mg and Si.

The low temperature sintering ceramic composition is a ceramiccomposition typically expressed by a composition formula:a(xCaO·(1−x)MgO·ySiO₂)·bBi₂O₃ ·cLi₂O(in the formula, a, b, and c represent the percentage by mass, andsatisfy the following relationships:a+b+c=100,60<a≦98.6,1≦b<35,0.4≦c<6,x and y represent a molar ratio,0≦x≦1,x:y is from 1:1 to under 1:2.5.)

Incorporation of Bi₂O₃ and Li₂O into the complex oxide that contains Ca,Mg, and Si can produce a Bi₂O₃—SiO₂ system liquid phase and a Li₂O—SiO₂system liquid phase therein when the above mixture was heated, and theliquid phase reaction occurring at that time can perform the sinteringthereof at a temperature in the range of 850 to 1,000° C.

The total amount of CaO, MgO, and SiO₂ in the low temperature sinteringceramic composition according to the present invention is from over 60%by mass to 98.6% by mass. When CaO, MgO, and SiO₂ are contained lessthan necessary, the characteristic of high Qf, obtained because thecrystal phase containing these oxides assumes the primary phase therein,is deteriorated. When these oxides are contained more than necessary,the properties of low temperature sintering are lost. Though thepreferred content depends on the amount of other components and thedesired characteristics (for example, dielectric constant, Qf, strength,sintering temperature, or bulk density the, i.e., relative valueobtained by dividing the observed density with the theoretical densitycalculated for a completely dense material on which prime importance isplaced), the content thereof is usually from 75% by mass to 98% by mass,more preferably from 80% by mass to 96% by mass, and further preferablyfrom 85% by mass to 95% by mass. The amount ratio of CaO and MgO can bearbitrarily determined, and either of the two oxides may not becontained. However, the molar ratio of (CaO+MgO) and SiO₂ is in therange of from 1:1 to under 1:2.5.

The total amount of Bi₂O₃ is from 1% by mass to under 35% by mass, andthat of Li₂O is from 0.4% by mass to under 6% by mass. That of Bi₂O₃ ispreferably 1.5 to 25% by mass, and is more preferably 3 to 15% by mass.That of Li₂O is preferably 0.4 to 5% by mass, and is more preferably inthe range of 0.5 to 3% by mass.

When Bi₂O₃ is contained less than necessary, the low temperaturesintering properties cannot be realized. When Bi₂O₃ is contained morethan necessary, the bulk density becomes 4 g/cm³ or more, and furtherthe dielectric constant becomes disadvantageously high because2Bi₂O₃·3SiO₂ becomes a primary phase. When Li₂O is contained less thannecessary, the low temperature sintering properties cannot be realized.On the contrary, when Li₂O is contained more than necessary, thedielectric loss in a high frequency region of 16 GHz becomes 1.0×10⁻³ ormore; accordingly, a high Qf value cannot be obtained.

A complex oxide of Ca, Mg, and Si may be any one as far as the molarratio between CaO, MgO, and SiO₂ satisfies the above range; however, acomplex oxide that satisfies 1≦n≦2 when expressed by (CaO, MgO).nSiO₂ ispreferably selected as a primary component. A complex oxide crystal atn=2 (CaO.MgO.2SiO₂) is known as diopside, and complex oxide crystals atn=1 (CaO.SiO₂) and (MgO.SiO₂) are known as wollastonite and enstatite,respectively.

Accordingly, the low temperature sintering ceramic according to theinvention, while preferably primarily containing a diopside systemcrystal phase, an enstatite system crystal phase, and/or a wollastonitesystem crystal phase, is further composed mainly of a Bi₂O₃—SiO₂ systemcrystal phase and a Li₂O—SiO₂ system crystal phase. Here, the “diopsidesystem crystal phase” denotes diopside and crystal phases similar tothis, and may contain the similar type of crystal phases composed of thecomponents of the ceramic composition. The situations are similar alsoto a wollastonite system crystal phase, an enstatite system crystalphase, a Bi₂O₃—SiO₂ system crystal phase, and a Li₂O—SiO₂ system crystalphase.

The specific molar ratios of the respective phases, as far as the targetvalues of the physical properties can be realized by the phases, are notrestricted; however, ordinarily, the diopside system crystal phase, theenstatite system crystal phase, and/or the wollastonite system crystalphase are contained in an amount of 60% or more of a total volume of theceramic, preferably in an amount of 80% or more, more preferably in anamount of 90% or more, and still more preferably in an amount of 95% ormore.

Furthermore, as far as the effect of the invention is not lost, a SiO₂system crystal phase or a similar system crystal phase and an amorphousmaterial or a similar material may be contained.

The low temperature sintering ceramic according to the invention has aQf value of 10,000 or more, and is densified to have a relative densityof 95% or more by being sintered in the temperature range of 850° C. to1,000° C.

(B) Method of Fabricating Low Temperature Sintering Ceramic

The low temperature sintering ceramic according to the invention can befabricated by mixing a raw material powder including the followingchemical composition based on percent by mass: a mixture and/or acomplex oxide of CaO, MgO and SiO₂, in which (CaO+MgO) and SiO₂ arecontained at a molar ratio of from 1:1 to 1:2.5 (wherein, either one ofCaO and MgO may not be contained): from over 60.0% to 98.6%; Bi₂O₃: from1% to under 35%, and Li₂O: from 0.4% to under 6%; calcining the mixturebelow 850° C., preferably 750° C. to 850° C.; suitably conductingpulverizing; and perfoming molding into a predetermined shape followedby being sintered at a temperature in the range of from 850° C. to1,000° C.

CaO, MgO, and SiO₂ that are used as starting raw materials can be addednot only in the form of oxide powder of the respective elements, butalso in the form of complex oxide such as Mg₂SiO₄, carbonates, acetates,nitrates, and the like that can form an oxide in the course of thesintering.

To the above raw material of primary components, Bi₂O₃ powder and Li₂Opowder are added as the sintering additive such that the oxide powdersare contained in the above concentration range, preferably in thepreferable concentration range, followed by mixing. Bi₂O₃ and Li₂O alsocan be also added not only in the form of oxide powder of the respectivemetals, but also in the form of carbonates, acetates, nitrates and thelike that can form an oxide in the course of the sintering.

Raw material powders of CaO, MgO, SiO₂, Bi₂O₃, Li₂O and the like, inorder to increase the dispersion characteristics thereof and to obtain adesirable dielectric constant and a low dielectric loss, are preferablypulverized into fine powders of 2.0 μm or less, particularly 1.0 μm orless.

The powder mixture obtained by mixing the ingredients at the above ratiois mixed with an appropriately added binder. Then, the mixture is moldedinto an arbitrary shape by means of such as a mold pressing, extrusionmolding, doctor blade, rolling method, and any other suitable method,and is sintered in an oxidizing atmosphere or a nonoxidizing atmosphereof N₂, Ar, and the like at a temperature of 850° C. to 1,000° C.,particularly 850° C. to 950° C. for 1 to 3 hr, thereby enabling themixture to be densified so as to have a relative density of 95% or more.When the sintering temperature at that time is lower than 850° C., theceramic cannot be sufficiently densified. On the other hand, when itexceeds 1,000° C., though the densification can be attained, it becomesdifficult to use low melting point conductors such as Ag, Au, Cu and thelike as the wiring material.

According to the method according to the invention, a more activesolid-liquid reaction proceeds between a solid phase containing complexoxides of Ca, Mg, and Si and a liquid phase containing a Bi₂O₃—SiO₂system liquid phase and a Li₂O—SiO₂ system liquid phase; as a result,the ceramic can be densified with a slight amount of sintering aid. Forthis reason, an amount of an amorphous phase in grain boundary thatcauses an increase in the dielectric loss can be suppressed to theminimum amount. As mentioned above, according to the fabricating methodaccording to the invention, in the ceramic, the diopside system crystalphase that contains at least Ca, Mg, and Si, the enstatite systemcrystal phase, and/or the wollastonite system crystal phase, theBi₂O₃—SiO₂ system crystal phase, and the Li₂O—SiO₂ system crystal phasecan be precipitated, and thereby, a ceramic for high frequency having adielectric constant that can be controlled to 9 or less even atapproximately 16 GHz, and having a low dielectric loss, in other wordshaving a high Qf value can be obtained. Moreover, the adjustment ofamount ratio of (CaO+MgO):SiO₂ enables the easy adjustment of thedielectric constant of the ceramic. For example, when the molar ratio of(CaO+MgO):SiO₂ is in the range of 1:1.75 to 1:2.5, it is possible toreduce the relative dielectric constant to seven or less, and when themolar ratio of (CaO+MgO):SiO₂ is in the range of 1:1 to 1:1.75, it ispossible to adjust the relative dielectric constant within the range of7 to 9.

(C) Applications of Ceramic Composition

The ceramic composition according to the invention can be sintered at atemperature of 850 to 1,000° C. Therefore, the ceramic can be used asthe insulating substrate for a printed wiring board where wiring iscarried out by using particularly Ag, Au, Cu, and the like. When aprinted wiring board is fabricated by use of such ceramic composition, apowder mixture compounded as mentioned above is formed into a greensheet for use in the formation of insulating layer by means of a knowntape formation method, for example, a doctor blade method and extrusionmolding method. Thereafter, on the surface of the green sheet, by use ofa conductive paste containing at least one type of metal, in particular,Ag powder, of Ag, Au and Cu, as a wiring circuit layer, a wiring patternis printed in the form of a circuit pattern by means of a screenprinting method, for example. Optionally, through holes and via holesmay be formed through the sheet, followed by filling the holes with theabove conductive paste. Thereafter, a plurality of green sheets arelaminated under pressure, followed by sintering the sheets under theabove conditions, and thereby the wiring layer and the insulating layercan be co-sintered.

Accordingly, the present invention also encompasses electroniccomponents containing these circuits. The wiring pattern may alsoinclude a pattern comprising a material other than the materialsmentioned above as long as it can be used under the sintering condition.Typical but not limiting examples thereof include a resistor formed of amaterial having a high-melting point. The electronic component may becomposed of these wiring patterns or contain discrete devices mountedthereon.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be specifically described by way of examplesand comparative examples. However, the present invention is not limitedonly to these examples.

EXAMPLES 1 TO 41

Compound mixtures composed of CaO, MgO (Mg₂SiO₄), SiO₂, Bi₂O₃, andLi₂CO₃ each having an average particle diameter of 1 μm or less wereeach mixed so as to obtain a content ratio in terms of oxide as shown inTables 1 to 2. This mixture was calcined at 800° C. for 5 hours,suitably pulverized and added with an organic binder, a plasticizer, andtoluene, followed by preparing green sheets each having a thickness of150 μm by means of the doctor blade method. Then, five of the greensheets were stacked and subjected to thermocompression bonding under apressure of 150 kg/cm2 at 70° C. The obtained laminate bodies, afterheating the sheets in air at 500° C. so that the organic components maybe decomposed and/or and evaporated, were sintered in air under theconditions shown in Table 1, thereby obtaining ceramics formulti-layered substrate.

The obtained sintered bodies were evaluated for the dielectric constantand the dielectric loss according to the following methods. Themeasurements were performed according to JIS R1627 “Testing method fordielectric properties of fine ceramics at microwave frequency.” Theceramic for multi-layered substrate use was cut into a disc-like samplehaving a diameter of 1 to 5 mm and a thickness of 2 to 3 mm, and bothend faces of the disc-like sample were short circuited by use of twoparallel conductive plates to thereby form a dielectric resonator. Theresonance characteristics and the no-load Q at TE011 mode of thedielectric resonator were measured in the range of 16 to 20 GHz by useof a network analyzer (Model 8722C manufactured by Hewlett-PackardCorp.) followed by calculating the dielectric constant and thedielectric loss (tans) further followed by calculating the Qf value froma measuring frequency and Q (=1/tanδ). The complete results are shown inTables 1 to 2.

Furthermore, each of the samples was subjected to X-ray diffractometry,and comparisons between the X-ray diffraction peaks of the samples andthat of standard samples were made to identify the phases constitutingthe ceramics. The comparisons confirmed the existence in the ceramics,of each of the diopside crystal phase (CaO·MgO·2SiO₂), wollastonite(CaO·SiO₂) crystal phase, and/or enstatite crystal phase (Mg·SiO₄),Bi₂O₃—SiO₂ system crystal phase (typically, eulytite (2Bi₂O₃.3SiO₄), andLi₂O—SiO₂ system crystal phase.

As is apparent from the above results, all of the ceramics according tothe invention that include CaO, MgO, SiO₂, Bi₂O₃ and Li₂O within thescope of the invention, and that further have the diopside crystalphase, the wollastonite crystal phase and/or the enstatite systemcrystal phase, the Bi₂O₃—SiO₂ system crystal phase, and the Li₂O—SiO₂system crystal phase, which are mainly precipitated therein as crystalphases, exhibit excellent values of a dielectric constant of 9 or lessand a Qf value of 10,000 or more.

COMPARATIVE EXAMPLES 1 TO 6

Compound mixtures composed of CaO, MgO, SiO₂, Bi₂O₃, and Li₂CO₃ eachhaving an average particle diameter of 1 μm or less were each mixed soas to obtain a content ratio in terms of oxide as shown in Table 2. Asin the case of Examples 1 to 4, these compositions were sintered underthe conditions shown in Tables 1 to 2, to thereby obtain ceramics formulti-layered substrate use. The results of the dielectric constantsthereof measured as similarly in Examples are also shown in Tables 1 to2.

A sample where Bi₂O₃ and Li₂O were not added could not be sintered at alow temperature (Comparative Example 1), and a sample where Bi₂O₃ wasadded in an amount of less than 1% by mass (Comparative Example 2) and asamples where Li₂O was added in an amount of less than 0.4% by mass(Comparative Example 4) were not sintered at a sintering temperature inrange of the present invention. The bulk density tends to increase withan increase in the content of Bi, and the bulk density reached nearly4.0 at a Bi₂O₃ content of 35% by mass (Comparative Example 5).Meanwhile, when the amount of Li₂O reached 6% by mass (ComparativeExample 3), the dielectric loss becomes large, and the Qf valuedecreased to less than 10,000. Moreover, in the sample where(CaO+MgO):SiO₂ exceeds 1:2.5 (Comparative Example 6), the Qf valuethereof decreases to less than 10,000.

TABLE 1 Composition Composition Additive Sintering Composition (molorratio) (% by mass) (% by mass) temperature No. ratio CaO MgO SiO₂ CaOMgO SiO₂ Bi₂O₃ Li₂O (° C.) Example 1 93 1 1 2.5 21.1 15.2 56.7 5.0 2.0883 2 93 1 1 3 18.8 13.5 60.6 5.0 2.0 883 3 93 1 1 3.5 17.0 12.2 63.85.0 2.0 883 4 95 1 1 2.5 21.6 15.5 57.6 3.6 1.4 883 5 91 1 1 2.5 20.714.9 55.4 6.4 2.6 883 6 89 1 1 2.5 20.2 14.5 54.2 7.9 3.1 883 7 90 1 12.5 20.5 14.7 54.8 8.0 2.0 883 8 90 1 1 2.5 20.5 14.7 54.8 6.0 4.0 883 995 1 1 2.5 21.6 15.5 57.9 4.5 0.5 950 10 95 1 1 3 19.3 13.8 61.9 4.5 0.5950 11 95 1 1 3.5 17.4 12.5 65.1 4.5 0.5 950 12 95 1 1 2.5 21.6 15.557.9 4.0 1.0 890 13 95 1 1 3 19.3 13.8 61.9 4.0 1.0 890 14 95 1 1 3.517.4 12.5 65.1 4.0 1.0 890 15 95 1 1 2.5 21.6 15.5 57.9 4.5 0.5 955 1694.5 1 1 2.5 21.5 15.4 57.6 4.5 1.0 893 17 93.5 1 1 2.5 21.3 15.3 57.04.5 2.0 893 18 90.5 1 1 2.5 20.6 14.8 55.1 9.0 0.5 893 19 86 1 1 2.519.6 14.1 52.4 13.5 0.5 893 20 94.5 1 1 2.5 21.5 15.4 57.6 5.0 0.5 94721 93.5 1 1 2.5 21.3 15.3 57.0 6.0 0.5 947 22 94 1 1 2.1 23.7 17.0 53.35.5 0.5 945 23 94 1 1 2.3 22.5 16.1 55.4 5.5 0.5 945 24 94 1 1 2.7 20.414.6 59.0 5.5 0.5 945 Holding Water Bulk time absorption densityFrequency Dielectric No. (hr) (%) (g/cm³⁾ (GHz) constant Q Qf Example 11 0.0 3.15 17.4 7.56 880 15312 2 1 0.0 3.13 17.6 7.21 799 14062 3 1 0.03.08 18.0 6.88 741 13345 4 1 0.0 3.19 17.4 7.59 1038 18054 5 1 0.0 3.2217.4 7.60 773 13447 6 1 0.0 3.22 17.3 7.72 966 16719 7 1 0.0 3.26 17.47.72 880 15310 8 1 0.0 3.22 17.2 7.77 735 12633 9 1 0.0 3.17 17.4 7.451063 18493 10 1 0.0 3.09 18.4 6.99 1025 18856 11 1 0.0 3.04 18.5 6.77809 14972 12 1 0.0 3.11 18.0 7.30 868 15615 13 1 0.0 3.09 18.1 6.98 105119018 14 1 0.0 3.00 19.2 6.54 939 18029 15 1 0.0 3.13 17.7 7.41 117720789 16 1 0.0 3.17 17.3 7.48 1518 26312 17 1 0.0 3.19 17.3 7.56 91615851 18 1 0.0 3.26 17.4 7.56 1851 32138 19 1 0.0 3.44 17.4 7.84 181231472 20 1 0.0 3.16 18.0 7.31 959 17272 21 1 0.0 3.20 17.9 7.44 87215599 22 1 0.0 3.26 17.2 7.79 1247 21395 23 1 0.0 3.20 17.4 7.60 108718958 24 1 0.0 3.17 17.7 7.28 1109 19639

TABLE 2 Composition Composition Additive Sintering Composition (molorratio) (% by mass) (% by mass) temperature No. ratio CaO MgO SiO₂ CaOMgO SiO₂ Bi₂O₃ Li₂O (° C.) Example 25 96 1 1 2.5 21.8 15.7 58.5 3.0 1.0959 26 98 1 1 2.5 22.3 16.0 59.7 1.0 1.0 959 27 90.5 1 1 2.5 20.6 14.855.1 4.5 5.0 900 28 93.5 1 1 2.1 23.6 16.9 53.0 5.5 1.0 900 29 92.5 1 12.1 23.3 16.7 52.4 5.5 2.0 949 30 93.5 1 1 2 24.2 17.4 51.9 5.5 1.0 96331 93.5 1 1 2.2 22.9 16.5 54.1 5.5 1.0 908 32 93.5 1 1 2.3 22.4 16.155.1 5.5 1.0 908 33 95 1 1 4 15.8 11.4 67.8 4.5 0.5 943 34 94.5 0.2 1.82.2 4.9 31.7 57.9 4.5 1.0 908 35 94.5 0.5 1.5 2.2 12.0 25.9 56.6 4.5 1.0908 36 94.5 0.8 1.2 2.2 18.8 20.3 55.4 4.5 1.0 908 37 94.5 1.3 0.7 2.229.5 11.4 53.5 4.5 1.0 882 38 94.5 1.6 0.4 2.2 35.6 6.4 52.5 4.5 1.0 88239 94.5 0 2 2.2 0.0 35.8 58.7 4.5 1.0 903 40 94.5 1.8 0.2 2.2 39.6 3.251.8 4.5 1.0 939 41 94.5 2 0 2.2 43.4 0.0 51.1 4.5 1.0 861 Com- 1 100 11 2 21.5 15.5 46.1 0.0 0.0 1280 para- 2 98.5 1 1 2 25.5 18.3 54.7 0.51.0 963 tive 3 89.5 1 1 2.5 20.4 14.6 54.5 4.5 6.0 949 Example 4 95.2 11 2.5 21.7 15.6 58.0 4.5 0.3 957 5 64.5 1 1 2.5 14.7 10.5 39.3 35.0 0.5895 6 95 1 1 5 13.4 9.6 71.9 4.5 0.5 943 Holding Water Bulk timeabsorption density Frequency Dielectric No. (hr) (%) (g/cm³⁾ (GHz)constant Q Qf Example 25 1 0.0 3.14 17.9 7.33 1115 19920 26 1 0.0 3.0917.9 7.18 1421 25452 27 1 0.0 3.13 17.2 7.68 822 14176 28 1 0.0 3.2717.3 7.90 2077 36019 29 1 0.0 3.25 17.2 7.96 875 15088 30 1 0.0 3.2817.8 8.20 792 14127 31 1 0.0 3.23 18.2 7.81 1804 32865 32 1 0.0 3.2518.4 7.67 1581 29066 33 1 0.0 2.97 18.7 6.47 666 12434 34 1 0.0 3.1718.9 7.12 1738 32877 35 1 0.0 3.20 18.6 7.40 1551 28794 36 1 0.0 3.2618.2 7.72 1569 28542 37 1 0.0 3.14 17.0 7.63 1188 20212 38 1 0.0 3.0517.3 7.21 1869 32410 39 1 0.0 3.16 18.0 6.95 1685 30396 40 1 0.0 2.9718.0 7.02 1025 18421 41 1 0.0 2.90 18.5 6.81 1233 22782 Com- 1 3 0.03.23 17.8 7.64 3684 65579 para- 2 1 Not sintered tive 3 1 0.0 3.09 17.47.67 522 9053 Example 4 1 Not sintered 5 1 0.0 3.98 16.2 9.15 1334 215716 1 0.0 2.96 19.1 6.24 377 7191

COMPARATIVE EXAMPLE 7

A composition that was prepared in the same conditions as in Example 28except that B is used in place of Bi, was sintered at almost the sametemperature (921° C.). This composition corresponds to the one disclosedin JP-A-2001-278657, except that B₂O₃ was added when the calcination wasperformed at 800° C. in this comparative example while inJP-A-2001-278657, only the principal ingredients (CaO, MgO, and SiO₂)were calcined at 1100° C., added with B₂O₃ and then sintered. As aresult, the Q value was 523 at 16.7 GHz, and the Qf value (8749) wasless than 10,000. The specific composition and results thereof are shownin Table 3 (The composition and results of Example 28 are the same asthe ones shown in Table 2).

As mentioned above, the composition is calcined at 1,100° C. or more,before addition of the additive component (B₂O₃ and the like) in orderto produce a diopside crystal phase in the Examples disclosed inJP-A-2001-278657. However, as is apparent from the results ofComparative Example 7, the Qf value decreases greatly when thediopside-crystal-constituting components (the oxides of Ca, Mg, and Si)are added with B₂O₃ without preliminarily having been subjected tocalcination, and all the ingredients are calcined as a whole, and then(after pulverized and molded) sintered. In contrast to this, accordingto the present invention in which Bi₂O₃ is used as an additivecomponent, even though the composition is calcined as a whole, and then(after pulverized and molded) sintered, a ceramic having a high Qf valueis obtained.

TABLE 3 Composition Composition Additive Sintering Composition (molorratio) (% by mass) (% by mass) temperature No. ratio CaO MgO SiO₂ CaOMgO SiO₂ Bi₂O₃ Li₂O (° C.) Ex. 28 93.5 1 1 2.1 23.6 16.9 53.0 5.5 1.0900 Com. 7 93.5 1 1 2.1 23.6 16.9 53.0 5.5 1.0 921 Ex. Holding WaterBulk time absorption density Frequency Dielectric No. (hr) (%) (g/cm³⁾(GHz) constant Q Qf Ex. 28 1 0.0 3.27 17.3 7.90 2077 36019 Com. 7 1 0.03.07 16.7 7.55 523 8749 Ex.

INDUSTRIAL APPLICABILITY

As detailed above, the low temperature sintering ceramic compositionaccording to the invention, as a result of the use of oxides of Bi andLi as a liquid phase formation component, realized the low temperaturesintering properties in the ceramic composition that includes as themain phase the diopside system crystal phase, the enstatite systemcrystal phase and/or the wollastonite system crystal phase. Furthermore,it was found that even when Bi₂O₃ was incorporated in a large amount,the dielectric loss is not deteriorated. Thereby, a high Qf value can berealized. Accordingly, the ceramic composition according to theinvention, is most suitable as a low loss LTCC (low temperatureco-firing ceramics) material having the dielectric constant (9 or less)that can be utilized in a high frequency region of 16 GHz or more andhaving a high Qf (10,000 or more), and thereby can be used in varioustypes of microwave circuit elements and the like. Further, because theceramic can be fabricated from the ceramic composition, merely bysintering all of the components at 850° C. to 1,000° C., the wiringcomposed of Cu, Au, Ag, and the like can be formed by means ofco-firing, and the energy cost and environmental load that are requiredfor manufacturing the ceramic are small.

1. A low temperature sintering ceramic composition comprising thefollowing chemical composition based on percent by mass: CaO, MgO, andSiO₂ in total: over 60% to 98.6%, wherein either of CaO and MgO may notbe contained; Bi₂O₃: from 1% to under 35%; and Li₂O: from 0.4% to under6%; wherein (CaO+MgO) and SiO₂ are contained in the molar ratio of from1:1 to under 1:2.5.
 2. A low temperature sintering ceramic compositionaccording to claim 1, wherein CaO, MgO, and SiO₂ are contained at leastin part as a complex oxide of Ca and/or Mg and Si.
 3. A low temperaturesintering ceramic composition according to claim 2, wherein the complexoxide containing Ca and/or Mg and Si comprises a diopside(CaO.MgO.2SiO₂) system crystal phase, an enstatite (MgO.SiO₂) systemcrystal phase, and/or a wollastonite (CaO.SiO₂) system crystal phase. 4.A low temperature sintering ceramic composition according to claim 1,wherein the low temperature sintering ceramic composition has adielectric constant of 9.0 or less and a Qf value of 10,000 or more, at16 GHz or more.
 5. An electronic component comprising a wiring patternon the low temperature sintering ceramic composition according toclaim
 1. 6. The electronic component according to claim 5, wherein thewiring is formed by sintering a conductive paste containing at least onemetal selected from the group consisting of Ag, Au and Cu.
 7. Afabricating method of a low temperature sintering ceramic compositioncomprising: mixing a raw material powder comprising the followingchemical composition based on percent by mass: CaO, MgO, and SiO₂ intotal: over 60% to 98.6%, wherein either of CaO and MgO may not becontained; Bi₂O₃: 1% to under 35%; and Li₂O: from 0.4% to under 6%, suchthat (CaO+MgO) and SiO₂ are contained in the molar ratio of from 1:1 tounder 1:2.5; calcining the mixture below 850° C.; molding the materialpowder into a predetermined shape; and sintering the molded materialpowder at a temperature of 850° C. to 1,000° C.
 8. The method accordingto claim 7, wherein the raw material powders are fine powders having aparticle size of 2.0 μm or less.